On circular power saws it is a common practice to provide a kickback clutch to prevent the saw from kicking out of the work if the blade jams and stops. In blade mountings of this type, the blade is not keyed to the drive shaft but rather is clamped between a shoulder on the drive shaft and a washer, the clamping force being provided by a spring washer retained by a screw threaded axially into the end of the drive shaft. The arrangement functions as a torque-limiting clutch so that, upon jamming of the blade in the work, the driving torque will not cause the saw to kick out of the work. When properly assembled and adjusted, such a clutch is an effective safety feature. If, however, the mounting screw is tightened excessively or if the spring washer is replaced by a different washer, the effectiveness of the clutch may be defeated. Brodie, U.S. Pat. No. 3,266,535, provides a solution for the problem of overtightening by the use of a set screw serving as a stop to limit the depth to which the blade screw may be threaded into the spindle bore. It is possible with the arrangement of the Brodie patent, however, for the user to inadvertently replace the spring washer with a different washer thereby defeating the safety feature of the arrangement. It is also possible in this arrangement to substitute a shorter screw for the blade screw, again rendering the safety feature ineffective.
Among the objects of the present invention are the provision of a saw blade mounting assembly of the kickback clutch type in which the substitution of an incorrect component which would defeat the intended purpose of the assembly is precluded; the provision of a saw blade mounting assembly in which that portion of the assembly which is removed from the saw when a blade is being changed is a permanent subassembly, thereby eliminating the risk of loss of the individual components thereof; and the provision of a kickback clutch saw blade mounting incorporating visual means for indicating when the clutch is properly tensioned.